Local factors have a greater influence on the abundance of alfalfa weevil and its larval parasitoids than landscape complexity in heterogeneous landscapes

• Published in: Landscape ecology 2024-08, Vol.39 (8), p.143, Article 143
• Main Authors: Levi‑Mourao, A., Meseguer, R., Nogueira Madeira, Filipe José, Martinez‑Casasnovas, J.A., Costamagna, A.C., Pons, X.
• Format: Article
• Language: English
• Subjects: Abundance; Age composition; Alfalfa; alfalfa pest; Bathyplectes spp; Biological control; Biological effects; Biomedical and Life Sciences; Buffers; Configurations; Curculionidae; Density; Ecology; Environmental Management; Hypera postica; Influence; Irrigation pipes; Irrigation systems; landscape composition; landscape confguration; Landscape Ecology; Landscape/Regional and Urban Planning; Larvae; Life Sciences; Natural enemies; Nature Conservation; Parasitism; parasitism rate; Parasitoids; Pests; Research Article; Sprinkler irrigation; Sustainable Development; Variables
• ISSN: 1572-9761; 0921-2973; 1572-9761
• DOI: 10.1007/s10980-024-01949-2

Context The alfalfa weevil Hypera postica Gyllenhal (Coleoptera: Curculionidae) is one of the most destructive pests of alfalfa worldwide. Both local and landscape-scale factors can significantly infuence crop pests, natural enemies, and the efectiveness of biological control services, but the relative infuence of these factors is unclear. Objectives We investigated the infuence of the local variables and surrounding landscape composition and configuration on the abundance of alfalfa weevil, and on the abundance and parasitism rates of its larval parasitoids, Bathyplectes spp. Methods We sampled 65 commercial alfalfa fields along the Ebro Basin, Spain, over a period of 3 years, recording the field characteristics and landscape structure at three buffer radii of 250, 500 and 1000 m from the center of each field. Results The abundance of weevil larvae was positively associated with the field perimeter and with the uncut alfalfa surrounding the pipes of the sprinkler irrigation system, but only one configuration variable was positively correlated: the alfalfa edge density. No local characteristics or landscape structures were associated with the abundance of adult weevils. The abundance of Bathyplectes spp. adults was positively associated to local factors such as the densities of alfalfa weevils and aphids. Few landscape structure variables, such as alfalfa edge density and Simpson’s Diversity Index, had explanatory value only at 250 m buffer radius. The rate of larval parasitism was affected by local variables, such as alfalfa weevil abundance and field age. Conclusion Our results provide, for the first time in the Mediterranean region and Europe, evidence of the relative importance of landscape structure and local factors on the abundance of the alfalfa weevil and its larval parasitoids, Bathyplectes spp. The strongest infuences were based on local characteristics. Springer Nature; Spanish Government; Universitat de Lleida; Fundação para a Ciência e a Tecnologia